Proteins do not pass through plasma membranes because:

Consider the mechanism of diffusion: Diffusion through the plasma membrane occurs for small, nonpolar molecules that can easily pass through the hydrophobic lipid bilayer. Large, polar molecules like proteins cannot diffuse through this barrier because their size and polarity prevent them from interacting favorably with the hydrophobic core of the membrane.

Evaluate the incorrect options: Proteins are not rapidly degraded by membrane enzymes, as enzymes are specific to their substrates and do not indiscriminately degrade proteins. Proteins are not electrically neutral; they often have charged regions. Additionally, proteins are not actively repelled by membrane carbohydrates, as carbohydrates primarily function in cell recognition and signaling.